A DC power supply unit (30) comprising a flashlight (32). A rechargeable cellular telephone battery (34) is provided, having a positive terminal (36) and a negative terminal (38). The rechargeable cellular telephone battery (34) is supported in the flashlight (32). An adjustable structure (40) is in the flashlight (32) for electrically connecting the flashlight (32) to the positive terminal (36) and the negative terminal (38) of the rechargeable cellular telephone battery (34), so that the rechargeable cellular telephone battery (34) can operate the flashlight (32). A facility (42) in the flashlight (32) is for electrically connecting the rechargeable cellular telephone battery (34) to a remote electrical device, so that the rechargeable cellular telephone battery (34) can operate the remote electrical device.